VPN is a technology used in order to establish secure connections, so called tunnels, between two points, or terminals, over an insecure data communication network. VPN may also be used to extend a private network and the resources contained in the network across public networks like the Internet. It enables a host computer to send and receive data across shared or public networks as if it were a private network with all the functionality, security and management policies of the private network. Again, tunnels or virtual point-to-point connections are established by means of which the host computer is enabled to send and receive data across shared or public networks.
However, packets being transmitted by means of a VPN may still suffer from information in the header of the packet being corrupted, which may affect the delivery of the packet to its final destination. With the header being corrupted is meant that the DSCP value in the header may have been altered or removed during its travel from a sender to a receiver.